Development

Communication / Bluetooth Low Energy:

» BLE 11 Characteristic notification slave

This example shows how notifying processes works. The program first make itself discoverable and connectable, waiting for incoming connections. Once connected, waits for notification subscribing events and, when they are found, the subscribed attribute is written five times to allow the master receive notification events. Then, it keeps waiting events till the connection is over.

Required Materials

2 x Waspmote
2 x Battery
2 x Bluetooth Low Energy module
2 x Bluetooth module antenna
1 x Expansion board (if socket 1 is used)
1 x SD card

Notes

- Socket 0 is used by default
- EEPROM is used in this example by default.
- Never unplug module while Waspmote is turned ON.
- Bluetooth module antenna should be connected.
- The battery must be connected in ANY example.
- This example can be executed in Waspmote v12 and Waspmote v15

Code

/*
 *  ------------------ [BLE_11] - Characteristic notification - Slave ----
 *  Explanation: This example shows how notifying processes works.
 *  The program first make itself discoverable and connectable, waiting 
 *  for incoming connections. Once connected, waits for notification 
 *  subscribing events and, when they are found, the subscribed attribute is 
 *  written five times to allow the master receive notification events.
 *  Then, it keeps waiting events till the connection is over.
 *
 *  Copyright (C) 2016 Libelium Comunicaciones Distribuidas S.L.
 *  http://www.libelium.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 * 
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS ARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 * 
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  Version:		1.0
 *  Design:			David Gascón
 *  Implementation:	Javier Siscart
 */

#include <WaspBLE.h>

// Auxiliary variable
uint8_t flag = 0;

void setup() 
{  
  USB.println(F("BLE_11 Example"));  

  // 0. Turn BLE module ON
  BLE.ON(SOCKET0);

}


void loop() 
{

  // 1. Make Waspmote visible to other BLE modules
  BLE.setDiscoverableMode(BLE_GAP_GENERAL_DISCOVERABLE);

  // 2. Make Waspmote connectable to any other BLE device
  BLE.setConnectableMode(BLE_GAP_UNDIRECTED_CONNECTABLE);
  USB.println(F("Waiting for incoming connections..."));

  // 3. Wait for connection status event during 30 seconds. 
  flag = BLE.waitEvent(30000);
  if (flag == BLE_EVENT_CONNECTION_STATUS)
  {
    USB.println(F("Connected!"));
    USB.println(F("Now Waspmote is connected as slave.")); 

    // 3.1 Parse the status event to find MAC of master device who initiated the connection.
    // NOTE: The event captured is stored in BLE.event array.
    uint8_t b = 5;
    for(uint8_t a = 0; a < 6 ; a++)
    {
      BLE.BLEDev.mac[a] = BLE.event[b+6];
      b--;
    }

    // 3.2 Print MAC of the Master device.
    USB.print(F("MASTER MAC Address: "));
    for(uint8_t i =0; i<6; i++)
    {
      USB.printHex(BLE.BLEDev.mac[i]);
    }
    USB.println();

    // 3.3 Parse connection handler. other information about status not used in this example.
    BLE.connection_handle = BLE.event[4];



    // 4 Now wait to other events forever. If disconnection is detected, exit loop and start again
    flag = 0;
    while(flag != BLE_EVENT_CONNECTION_DISCONNECTED)
    {

      // 4.1 Wait for indication event 
      USB.println(F("Waiting events..."));
      flag = BLE.waitEvent(5000);

      if (flag == BLE_EVENT_ATTRIBUTES_STATUS)
      {
        USB.println(F("Status event found"));

        // 4.2 look if one attribute has been indicated. flag = 1 means that notifications are enabled.
        /* status event structure:
         Field:   | Message type | Payload| Msg Class | Method |  Handle | Flags |
         Length:  |       1      |    1   |     1     |    1   |    2    |    1  |
         Example: |      80      |   10   |     02    |   02   |    00   |   01  |
         */

        if(BLE.event[6] == 1)
        {
          // 4.3 Subscription received.
          uint16_t handler = ((uint16_t)BLE.event[5] << 8) | BLE.event[4];
          USB.print(F("The master has subscribed to notifications of the attribute with handle: "));
          USB.println(handler, DEC);

          // 4.4 Change the attribute value 5 times each 5 seconds 
          USB.println(F("Change the attribute 5 times each five seconds"));        
          for (uint8_t a = 1; a <= 100; a++)
          {
            // 4.4.1 Write the local attribute which is indicated
            flag = BLE.writeLocalAttribute(handler, &a, 1);

            if (flag == 0)
            {
              USB.print(a, DEC);
              USB.println(" - Attribute changed");
            }
            else
            {
              USB.print("Error writing. flag =");
              USB.println(flag, DEC);
            }

            // 4.4.2 Wait 5 seconds till change the attribute value
            delay(5000);
          }

          flag = 0;
        }
        else 
        {
          // 4.2.1 Notify subscription not received
          USB.println(F("Master not subscribed"));
        }
      }
      else
      {
        // 4.1.1 Maybe Other event found
        if (flag != 0)
        {          
          // Other event received from BLE module
          USB.print(F("Event found. "));
          USB.print("flag = ");
          USB.println(flag, DEC);
        }
        else 
        {
          // no event received. 
          USB.println(F("No event received"));

        }
      }

      //4.5 get status. If not connected, exit.
      if (BLE.getStatus(BLE.connection_handle) == 0)
      {        
        BLE.disconnect(BLE.connection_handle);
        break;
      }

    } // end while

    // 4. if here, disconnected.
    USB.println(F("Disconnected"));    

  }
  else 
  {
    if (flag == 0)
    {
      // If there are no events, then no one tried to connect Waspmote
      USB.println(F("No events found. No devices tried to connect Waspmote."));
    }
    else
    {
      // Other event received from BLE module
      USB.print(F("Other event found. "));
      USB.print("flag = ");
      USB.println(flag, DEC);
    }
  }

  USB.println(); 
}

Output

H#
BLE_11 Example
Waiting for incoming connections...
Connected!
Now Waspmote is connected as slave.
MASTER MAC Address: CCC3EA6FA4B5
Waiting events...
Waiting events...
Waiting events...
Status event found
The master has suscribed to notifications of the attribute with handle: 44
Change the attribute 5 times each five seconds
1 - Attribute change notified
2 - Attribute change notified
3 - Attribute change notified
4 - Attribute change notified
5 - Attribute change notified
Waiting events...
Waiting events...
Waiting events...
Status event found
Master not subscribed
Waiting events...
Event found. flag = 15
Disconnected

Waiting for incoming connections...

Quick Publish: